The present invention relates to an automatic washing machine, more particularly to a dishwashing machine, of the type provided with a valve for distributing the flow of a circulating liquid within the hydraulic circuit of the washing machine.
In dishwashing machines in particular, a pump circulates the washing liquid within the machine and is capable of feeding two sprinkling vanes disposed at different heights within the washing machine. Thus, the delivery side of the circulation pump branches into two different ducts, each of which is connected to a respective sprinkling vane. In order to reduce the size of the pump motor as well as the size of the hydraulic circuit thereof, and further to deaden noise resulting from the impact of wash jets against dishes placed in the washing machine, it is preferable that the sprinkling vanes be fed alternately, rather than simultaneously.
Accordingly, it has been proposed, for example as disclosed in Italian patent application No. 21702 A/81 filed May 14, 1981 in the name of Industrie Candy S.p.A., to provide deflector means capable of connecting alternately the delivery side of the circulation pump to the different sprinkling vanes of a dishwashing machine. However, these deflector means are operated by the programmer of the washing machine by means of electromechanical devices or the like. This undesirably complicates the structure of the washing machine and deleteriously effects the reliability thereof.
These drawbacks can be avoided to a large extent by an arrangement as described in U.S. Pat. No. 3,868,835, wherein the circulation pump of the dishwashing machine is connected to two sprinkling vanes via a distributing valve having a closing element of the bistable type. In other words, when the pump is inoperative, the valve closing element is capable of leaning by gravity indiscriminately on a first valve seat or a second valve seat. The circulation pump is operated by the programmer of the washing machine intermittently and the valve seats, substantially .omega.-shaped, are positioned beneath two associated outlet ducts of the valve. Thus, during alternate operating phases of the pump the valve closing element obstructs alternately one or the other of the outlet ducts of the valve, while during shut-off or nonoperating intervals of the pump the valve element is placed alternately by gravity on the first or second valve seats. Advantageously, this distributing valve is operated directly by hydraulic pressure and by gravity, so that it is not necessary to provide electromechanical driving elements or the like. However, accurate operation and functioning of this valve is difficult to achieve. Thus, this valve is sensitive to the presence of dirt particles in the liquid flow which, even if deposited in small quantities in the areas of the valve seats, easily can prevent the closing element from operating properly.